JPS60231308A - Alumina magnetic head substrate material and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain the titled material which has a uniform structure and involves no fear of an edge portion thereof being broken when subjected to precision machining, by employing a compacted sintered material which consists essentially of a basic component composed of a titanium compound of TiC and TiO2 and the balance Al2O3, and three other specific components. CONSTITUTION:The titled material is obtained by employing a compacted sintered material which consists essentially of 100pts.wt. of a basic component composed of 30-40wt% of a titanium compound in which the percentage of TiO2/ (TiC+TiO2) is 5-15wt% and the balance Al2O3, 2.0-17.5pts.wt. of at least one kind of spinel represented by RO.Al2O3 (wherein R is at least one element selected from among Mg, Mn, Ni and Co), 0.2-2.0pts.wt. of ZrO2, 0.05-2pts.wt. of Y2O3, and 0.2 or less parts by weight (with respect to the entire composition) of an oxide impurity. The material has an average grain size of 1.3mum or less, an areal porosity of 0.5% or less, a flexural strength of 70kg/mm.<2> or more, and a hardness HRA of 93.0 or more. The ratio between the spinel and ZrO2 is within the range surrounded by KLMN in the figure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a material shed for a substrate for a thin film magnetic head (slider) and a method for manufacturing the same.

[Background] Conventionally, rad sliders for computer disks have been manufactured by processing ferrite block material, but ferrite material has low high-frequency magnetic permeability, and in recent years, the inductance of disk heads has been reduced to enable higher frequency In addition, the gap width is reduced to improve high-speed transfer and recording density.

Currently, composite materials have been developed that mainly consist of aluminum oxide and titanium carbide, and composite materials that have titanium nitride partially dissolved in titanium carbide. In addition to the above-mentioned main components, MgO, which is effective against aluminum oxide, is used to improve the sinterability of the material.

CaO, NiO, etc. are added.

In a thin film magnetic head, it is particularly required that when the substrate is finished with an ultra-precision mirror finish, even minute pores do not exist on the surface of the substrate, and that the substrate is easy to be precisely machined. Therefore, in order to prevent the presence of minute pores in a substrate with an ultra-precision mirror finish, the ceramic mixed powder is sintered to almost the theoretical density, and the bonding within the ceramic crystal particles is strong and a fine structure is formed. It must be something that you have. However, machinability of such a ceramic sintered body is extremely difficult. In order to solve this problem, for example, a material has been developed in which 5 parts by weight or less of MgO, Ni01, etc. are added as a free machining agent to the main components of aluminum oxide and titanium carbide based on 100 parts by weight of the main components.

(Unexamined Japanese Patent Publication No. 57-135772) [Problems and objectives of the prior art] However, these conventional ceramic substrate materials use free-machining agents such as MgO1NiO and Cr2O3 as a means of suppressing the growth of the original aluminum oxide crystal grains. The amount added is larger than when one or more types are added in an amount of about 1.0% by weight or less. Therefore, during mixing, due to the water solubility of magnesium oxide, it tends to solidify without being uniformly dispersed, and as a result, the structure of the ceramic sintered body tends to become non-uniform. There is a problem in that the edges are easily chipped during precision machining.

The present invention aims to provide a ceramic material for manufacturing a magnetic head (slider) substrate that solves the problems described in 1-.

[Summary of configuration of the invention] The alumina-based magnetic head substrate material of the present invention;
30-40% by weight of a titanium compound with a percentage of O2/(TiC+Ti02) of 5-15% by weight and the balance A
100 parts of a component consisting of 0.03 and a prescribed percentage of the following A
, B, and C components (however, the blending ratio of A and B components is K in Figure 1).
(within the range surrounded by
, 37Lm or less, area porosity 0.5% or less, bending strength 7
Characterized by being composed of a dense sintered body with a hardness of 0 kg/mm' or more and a hardness of 1 (RR93.0 or more: A component = ROA
Components - RO@A statement, 03 (R=Mg, Mn, Ni, C
One type of spinel represented by o (1 or more)
-17.5 parts by weight, component B = 0.2 to 2.0 parts by weight of ZrO precision adding T property imparting agent, component C = 0.05 to 2 parts by weight of Y203.

In this dense sintered body, AJ2203. Tic, TiC
2. Y2O3, ZrO2, and spinel are uniformly dispersed and the average crystal grain size is 0.7 to 1.3 JLm, and 90% or more of the number of crystal grains constituting the entire sintered body is within the range of 0.7 to 1.3 pm. It is preferable that the

The substrate material made of the dense sintered body has an average grain size of 1.57.
z, Tic below m, TiO2, average particle size 1, A text below Opm, 09, average particle size each lJ1. m or less of the above A,
It is obtained by sintering a mixed powder comprising components B and C in the composition ratio of the dense sintered body. Note that if the average particle size of the starting material is larger than the above, uniform dispersion becomes difficult, and the crystal grain size of the sintered body exceeds the specified value.

Note that the spinel/ZrO2 ratio (A/B ratio) is the first
It is necessary to set the range surrounded by KLMN in the figure.

Sintering is performed by pressure sintering, for example, hot press (or H
IP), and the sintering temperature is 1350-165
0℃, pressure is approximately 150-300kg/crn'()(
500 kg/c, m' according to IP'7
A predetermined sintered body can be obtained by sintering for a predetermined time in the above). Under the above sintering conditions, for example, 0.5
Sintering for ~2 hours is preferred. The substrate material of the present invention is based on an alumina-based ceramic sintered body and has a predetermined density, and has improved precision workability, ease of workability, toughness, and wear resistance.

[Preferred mode of implementation] The present invention will be explained below based on experiments.

<Experiment 1> (a) Experimental method and results α-A text with purity 99.9% and average particle size 0.3 pm, 0
3. T with a purity of 99.50% and an average particle size of 0.5 JLm
ic, TiO2 and Y2O3 and M g Oa A
41203, M n O” A n 203, N
Various blends of spinel and ZrO2 such as iO*Au703, CoO*AJ120a, etc. were mixed and pulverized at 20 hours using a ball mill mixer, and then thoroughly dried to be used as a raw material for sintering, and made into 50 x 50 mm squares. ,
Fill a graphite mold with various sintering materials listed in Section 42 (height 60mmcy), insert it into a high frequency coil, and 200kg/c at each predetermined temperature within the range of 1350°C to 1810°C in a non-oxidizing atmosphere. A pressure of m' was applied and held for 60 minutes, then the pressure was released, and it was left to cool to room temperature.
A desired sintered body of 0×5.5 mm was obtained. [TiO2/C
TiC+Ti07)]X100=10wt% MgO・
Table 1 shows the effects of A, 033.5 parts by weight, and Y, 03 added. Table 1 shows the (minimum) sintering temperature required to make the relative theoretical density of the sintered body 99.5% or more.

Table 2 shows Y2O in the sintered body in Table 1.

0.25 parts by weight of each sintered body was ground to a size of 50 x 50 x 4.5 mm, and a grinding performance test was conducted. The test conditions in this case are as follows. That is, various test pieces were fixed with a jig, a weight of 0.95 kg was attached to this via a pulley, and a resin diamond cutting wheel was used to cut the test pieces for 50 minutes using the force of a grinder.
The time required to cut a mm length was investigated.

Next, Y 20 : I = 0, 25 double edges, T i
O2/TiC+Ti02=10% by weight and Ti
C+TiO? MgO・A when is 20%, 30%, 40%
Sentence, 03. COO@A sentence, 0. .

MnO*Au203. NiO*Au203 from 1.75
The mixed powder shown in Table 3 containing 19 parts by weight was heated to 1620°C.
A sintered body of 50 x 50 x 5.5 mm with a relative theoretical density of 99.5% or more was obtained at 200 kg/crn" and held for 60 minutes.

This sintered body was ground to a size of 50 x 50 x 4.5 mm,
Table 3 shows the processability (cutting time) of various sintered bodies using the same method as shown in Table 2.

Table 4 shows Y, 03=0.25 parts by weight, TiO2/Ti
c+”r i 02.= 10% by weight, TiC+Ti
02 = 35% by weight constant, spinel Mg0eA as a free machinability imparting agent, 03. CoosAu203, M
n0aAJ1203 *NiO*A The results of investigating the effect of the amount of Zr02 added as an agent for imparting wear resistance and precision machinability to the amount of 203 added are shown. The test piece was prepared by sintering the mixed powder of description 4 at 200 k at a sintering temperature of 1620°C or less.
g/c, sintered to a theoretical density of 99.5% or more under hot press conditions of 60 minutes, 50
The workability (cutting time) of a test piece that was ground to a size of 50 x 4.5 mm was determined under the same conditions as in Table 2.

(Considerations) Regarding the relationship between the composition and quantitative ratio of the blended raw materials on hot press sintering, as shown in Table 1, for Y2O3, the hot press sintering temperature tends to decrease as y and o3 are added. The effect can be seen when the amount of Y2O3 exceeds 0.05 parts by weight.However, if Y2O3 exceeds the double R part, abnormal areas where crystal grains partially grow abnormally are seen in the structure of the sintered body. It is necessary to do so.

The composition of TiO2+Tic is TiO2,/(T
If the percentage of ic+Ti02) exceeds 15% by weight, the reaction with the graphite mold becomes significant, making it difficult to obtain a normal sintered body. In addition, if less than 5% wrinkles, A pattern 203-TiC-T
There is a tendency for the i02 series to be insufficiently sintered. Up to about 15% by weight, this is significant for the sinterability due to reactions with free carbon in the TiC raw material and reactions with other components;
This seems to be because if the percentage of iO2/TiC+TiO is too large, TiC is oxidized and the TiC crystal grains become coarse.

Furthermore, when the sintering temperature exceeds 1650°C, the growth of particles increases significantly, and the average particle size of the final sintered product is 1.
The sintering temperature must be 1650°C or lower, and the sintering temperature must be 1350°C or lower. If it is less than 1600°C, sintering is insufficient, and the temperature is preferably 1600°C or less.
A material having an average grain size of 1 μm or less and suitable for ultra-precision processing can be obtained.

From the grinding performance (investigation of cutting time) shown in Table 2, (T
As the amount of i C+ T i C2) increases, the grinding performance improves. Sometimes, the effect becomes greater when the amount is 20% by weight or more.

In addition, the various free-machining agents shown in Table 3 are spinels containing oxides, which are generally called grain growth suppressors and sintering accelerators.
2) If X100 is constant io weight%, (TiC+Ti0
2) Adjust the blending ratio to the range where grinding performance is excellent) 20.30
．． 40% by weight, Y, O, 0, 25 parts by weight constant,
Zr02 = 0.3 When looking at the grindability when the amount of free-machining agent added is changed under certain conditions, M
gO*Au, 03. CoO*Ai203.

2 Mn0*Au203, NiO*AJ1203 are each 2
．． It can be seen that the grindability suddenly improves when the temperature exceeds 0. Furthermore, if the additive amount exceeds 17.5 parts by weight, the grindability is improved, but chipping is likely to occur on the cut surface. This is thought to be because the sintered grain size becomes larger and the bonding force between crystal grains becomes weaker. Therefore, these free-cutting agents are 2.0-17
．． 5 parts by weight (more preferably 2.0 to 10.5 parts by weight)
It is desirable to add VA. (TiC+TiO2)20
%, the effect is not so noticeable, and the effect is large at 30% to 40%.

Table 4 is [TiO2/ (Tic+Tto,)]×10
0 is constant at 10% by weight, (Tio, +TiC) is constant at 35 parts by weight, Y2O is constant at 0.25 parts by weight, and the grindability is shown when the free machinability imparting agent and Zr02fi are varied. In Table 4, it can be seen that as the amount of Zr02 increases, the grindability becomes worse. However, this tendency is also related to the amount of free-cutting agent, and spinel/ZrO
It was found that if the compounding ratio of 2 is added within the range surrounded by KLMN in FIG. 1, there is no significant effect on free cutting performance.

In addition, in the materials of the various compounded components shown in Table 4, ZrO2, which is outside the scope of the present invention, is 0.1 part by weight and spinel is 1 part by weight.
．． The grindability of 75 and 19 parts by weight shows better grindability than the materials in the range of the present invention (particularly 19 parts by weight), but both have relatively large average grain sizes and have low bending strength. Since the material is inferior to the materials in the scope of the present invention in terms of hardness and hardness (HRA), it is superior in grindability. However, since all of these products outside the range have poor precision workability and relatively high porosity, they often do not satisfy the uses of the present invention.

It has been found that if the grindability is less than 100 seconds, the processing cost for precision processing is within an economical range, but if the grindability exceeds 100 seconds, the processing cost increases at an accelerating rate.

In other words, RO Fist AJ1202 and ZrO, materials within the range surrounded by KLMN in Figure 1 with limited blending amounts (K, L, M
As a result of investigating the precision machinability of the materials (including the N point), all of them showed sharp edges of the same amount as the present invention material (1) in Figure 2 (a), but the 3
Inferior to the inventive material shown in Figure (a), the state of the edge portion is third.
I checked a car approaching the state shown in Figure (b). In addition, K, L,
The coordinates of points M and N are as follows.

K (0,2,10,5) L (0,2,2,0) M (2,0,7,0) N (2,O,17,5) Below C b) The average grain size is This is because as the diameter exceeds 1.3 pm, the material strength tends to decrease, and micropores contained in the structure tend to gather together as crystal grains grow, forming relatively large pores.

Cracks and minute chips are likely to occur during precision machining, making it impossible to obtain ultra-precision machined products, and other drawbacks arise due to relatively large bores.

The existence of a relatively large bore not only makes precision machining difficult due to the occurrence of micro-defects, but also the risk of eaves formation due to sliding with the magnetic recording medium, and the magnetic particles accumulated in the bore may cause the magnetic recording data to be lost. may drop out,
must be avoided.

In addition, it is preferable that the crystal grain size is uniform and fine, but at least 90% of the uniformity of the crystal grains is 0.5 to 1.34.
It is preferable that the ratio is within a range of 1.3 pm.In particular, coarse grains exceeding 1.3 pm are present in large quantities, and if the ratio exceeds 10%, coarse grains may fall off or cause micro-chips during precision processing, which is undesirable.

The material strength is 70 kg/mm'' or more in terms of bending strength, which prevents cracking and chipping of edges during cutting and ultra-precision processing, or prevents tissue pooling (falling off).
It is necessary for etc. If the areal porosity exceeds 0.5%, the number of bores will increase and the strength of the material will decrease, while precision workability will deteriorate, so it is preferably 0.5% or less, preferably 0.
4% or less.

If the TTF rod strength is lower than 70 kg/mm, cracks, minute chips, and edge chips are likely to occur during precision machining, so it should be set at 7.
0 kg/mm'-1 preferably 75 kg/mm
' or more. If the hardness HRA is lower than 93.0, wear resistance will be insufficient and eaves will easily occur due to sliding movement with the magnetic recording medium, so it is necessary to have a hardness HRA of 93.0 or higher, preferably 93.0.
5 or more.

<Experiment 1> α-A text with a purity of 99.9% by weight and an average particle size of 0.37zm, 03, a purity of 99.5% and an average particle size of 0 and 5p.
A mixture of TiC, TiO2, Y2O3゜Z r02, Mg0-AJ120i, and other sintering accelerators and free machinability imparting agents was mixed and pulverized for 20 hours using a ball mill mixer. Thoroughly dry it and use it as a raw material for sintering,
Fill a graphite mold of 0 x 50 mm square and 60 mm height with the above various sintering raw materials, insert it into a high frequency coil, and 200 kg/kg at each predetermined temperature within the temperature range of 1350 ° C to 1600 ° C in an inert gas atmosphere. Apply crn' pressure 6
5 by holding for 0 minutes, then releasing the pressure and letting it cool.
A desired sintered body of 0x50x5.5 mm was obtained. Furthermore, Ti
The relative theoretical density was made to be at least 99.5% -L by hot pressing at 0z/(TiC+Ti0z)X100=10%.

Also, the composition is (TiC + TiO2) = 35% by weight and sentence A,
Y70:l for 100 parts by weight of 0365% by weight
, MgO*Au203, ZrO2, etc. were mixed and added as shown in Table 5.

Next, the sintered body thus obtained was formed into the shape shown in FIG. 3 using a diamond grindstone.

On the other hand, a pin-disc type wear test was conducted in combination with a donut-shaped ferrite disk formed to a diameter of φ45-φ1010X10.

Figure 4 shows the test method.
L, 03 TiC system) of the present invention and comparative example test pieces (AJLz 03 TiC system) were fixed in contact with the disk surface, and the disks were rotated and a load (W) was applied while they were in contact with each other. The wear amount and friction coefficient of the poem were measured.

The test conditions are shown below.

Load: 0.95kg Friction speed 191.7m/min Table 5 shows the results after 12,000 m.

<Experiment ■> Next, the sintered body 100 obtained by the method of Experiment II [35
(TiC+Ti02)-85Al2031-3.5Mg
0 ・An 203-0.25Y 203-0.3Zr
O2 and 100 [35(T+C+Ti02) 85 A
l20 a] -1,0M g O-0,25Y20
3 using a #400 diamond whetstone to 50X50X4.
FIG. 2 shows the state of the cut corner of the sample when it was ground to a size of 5 mm and then cut using a resin diamond cutting wheel under 9 conditions of 5 mm/sin.

[Consideration] TiO2/ (TiC+Ti02) When the percentage is 10% by weight, ((T i C + 'r i O2) 35% by weight + A sentence 20365% by weight)), Y2O3
10.25 parts by weight of MgO as a free machinability imparting agent.
・Al2O3 and MgO added, and Z r02
It can be seen that the wear resistance when in contact with ferrite is better in the case where MgO 03 and ZrO2 are added. It also has a small coefficient of friction. This is one of the important properties required of the magnetic herad slider material.

Next, Figure 2 shows the state when the T i CT i 02-AKL, 03 sintered body is cut with a diamond cutting wheel. It can be seen that it has a good shape and has excellent precision machinability.

<Experiment ■> 0 α-Al with a purity of 99.9% overlap and an average particle size of 0.3 m
l, 03. Purity 99.5% by weight Average particle size 0.5#L
m TiC, TiO7*Y20:l +MgO, Mg
O・Al2O3, Zro? (7) After mixing and pulverizing each of the sintering accelerator, free machinability imparting agent, and wear characteristic improvement imparting agent using a ball mill mixer for 20 hours, the mixture is thoroughly dried and sintered. As raw material, 50X5
A graphite mold of 0 mm square and 60 mm height is filled with various sintering materials listed in L, inserted into a high frequency coil, and heated to 200 kg at a temperature of 1350°C to 1600°C in a non-oxidizing atmosphere.
/cm" pressure was applied and held for 60 minutes, and then the pressure was released and allowed to cool to obtain a desired sintered body of 50 x 50 x 5.5 mm with a relative theoretical density of 99.5% or more.
O2/(TiC+Ti02)X100 was constant at 10% by weight, and Y2O3 was constant at 0.25 part by weight.

Next, the sintered body was cut and polished to a size of 4 x 8 x 25 mm, and the various objects shown in Table 6 were measured. Sample number 6 was sintered using a hot press until the relative theoretical density reached 95%, and then sintered using hot isostatic pressing (HIP) at 1450°C and 1800 kg.
/cnf sintered in an argon gas atmosphere.

Next, the secondary electron images of the surfaces of samples Nos. 4 and 14 after polishing are shown in FIGS. 5(a) and 6(a). The image is X-ray microanalysed,
The results observed with the iser are shown in Figures 5 (b) and 6 (b).
) are shown respectively.

[Discussion] The structure of Sample 4 is small and uniform with an average particle diameter of 0.8 pm. Furthermore, as seen in FIG. 5, it is seen that Mg in sample 4 is uniformly dispersed. -Actual sample No. 14
As is clear from FIG. 6(b), MgO is locally aggregated and is non-uniform. This is probably because MgO is water-soluble and tends to aggregate during drying after powder mixing. In FIG. 6(a) SEI, the three star-shaped marks are indented using a Vickers indenter to fix the sample measurement point.

11 Masaki Sho GO-231308 (7) JP-A Sho GO-231308 (10) 0\, HIP method is also effective as a sintering method for the structure of the present invention, as seen in Bemata sample positive, 6. Mn as a machinability imparting agent
O*Au,,oAVNipsAQ20:1,Coos
As a result of investigating HIP products in the composition range of the present invention for materials containing A and 03, the average crystal grain size was 1.3 pm.
It was confirmed that the material is effective as a substrate material for magnetic heads (sliders). FIG. 7 shows a photograph of the fracture surface structure of Sample 4.

[Brief explanation of the drawing]

Figure 1 is a graph showing the weight ratio of component B (Zr02, horizontal axis) and component A (spinel, vertical axis), Figure 2 (&),
(b) is a photograph (200x magnification) showing the fractured surfaces of an example of the present invention and a comparative example, respectively; Fig. 3 is a perspective view showing the shape of a test piece for measuring the amount of wear and coefficient of friction; Figure 4 is a schematic diagram of a test device for measuring wear amount and friction coefficient using the test piece shown in Figure 3. Figure 5 is a sample surface after polishing of one embodiment of the present invention (Sample M. 4 in Table 6). A secondary electron image (a) of the same part and a Mg characteristic X-ray image (b) of the same part are shown. FIG. 6 shows a 5EI secondary electron image (a) of the surface of a sample after polishing of a comparative example (Sample No. 14 in Table 6) and an Mg characteristic X-ray image of the same section. FIG. 7 shows a photograph of the fracture surface structure of Example 1 of the present invention (sample positive, 4) taken by a scanning electron microscope. Applicant Sumitomo Special Metals Co., Ltd. Japan Tungsten Co., Ltd. Agent Patent attorney Asami Kato t<Ln+→(-ichiji) Hajime Tsukasa CFOL) Rod 21 α! No. 31 Japan Tungsten Co., Ltd. 2-2-2 No. 31 Japan Tungsten Co., Ltd. Procedures No. 11 (spontaneous) August 1, 1985 Commissioner of the Japan Patent Office Mr. Michibu Uga Indication of the case 1988 Patent Application No. 88128 (Application filed on May 1, 1980) 2 Name of the invention Alumina-based magnetic head substrate material Nemi 1 and its manufacturing method 3 Relationship to the amended person's case Name of applicant Sumitomo Special Metals Co., Ltd. (1 other person) 5 Daily publication of amendment orders Voluntary issue 6 Number of inventions increased by amendment None 7 Contents of amendment subject to amendment 1. The scope of claims in the specification is amended as shown in the attached sheet. 2. Detailed explanation of the invention in the specification The following corrections will be made: (1) On page 3, line 14, “high-speed transfer” will be corrected as “high-speed data transfer.” (2) On page 4, line 8, “sintering” will be changed to “sintering.” (3) On page 5, line 16, "component" is corrected to "basic component." (4) On page 5, line 17, "1%" is corrected to "parts by weight." 5) Page 5, line 19, "%" is corrected to "part". (6) Page 6, line 3, "A component = ROJ is deleted. (7) Page 6, line 7, rZrOJ is corrected to “ZrO2”. (8) On page 8, line 19, “more influence” is amended to “yoru shadow”. (9) On page 9, line 12, “40% 11ν” is changed to “40%11ν”. "40%
, at 50%. (io) On page 10, line 9, amend "toshiko as a drug" to "as a drug." (11) On page 11, line 2, correct "heavy weight" to "parts by weight." (12) Page 11, line 14, rTic+Ti0J
Correct to (T i C+ T i 02 ) J. (13) Page 12, line 8, r T i C2J as “Ti
Correct to "O7". (14) Page 12, line 9, "20 to 11'i" is supplemented to 30J. (15) Page 14, line 18, “A sentence?02” is changed to “A sentence,
03”. (16) Page 17, line 14, “Experiment 1” is changed to “Experiment II”
Correct to J. (17) On page 20, line 6, "for" is corrected to "for 100 double sleeves." (18) On page 20, line 1 O, "abrasion resistance" is corrected to "comparison of abrasion resistance." (19) On page 22, line 14, "extremely" is corrected to "locally." (20) On page 22, line 16, "to" is corrected to "tokibanto". (21) The first line of Table 4 on page 25 is amended. 3. The brief description of the drawings in the specification is amended as follows. (1) On page 30, line 14, "break" is changed to "cut". (2) Page 30, lines 17-18, “Amount of wear, coefficient of friction”
Delete. Claim 1) The percentage of TiO2/(TiC+Ti02) is 5
30-40% by weight of a titanium compound that is ~15% by weight
100 parts by weight of this component, consisting of the remaining A sentence 203, the following A, B, and C components (however, the blending ratio of A and B components is within the range surrounded by KLMN in Figure 1) and 1. Contains 0.2 parts by weight or less of oxide impurities based on the total composition, average crystal grain size of 1.3 gm or less, porosity per area of 0.5% or less, bending strength of 70 kg/mm' or more, and hardness of HRA 93.
Alumina-based magnetic head substrate material made of a dense sintered body with a temperature of 0 or more: A component-RO・Auz 03 (R=Mg, Mn
. One type of spinel represented by Ni, Co, 1 m or more, 2.0 to 17.5 m thick. Component B - Z ro20.2 to 2.0 parts by weight. Component C - Y2O20.05 to 2 parts by weight. 2) A, Q2 0:I, Tic, TiO2. ￥203, ZrO2, and spinel are uniformly dispersed and the average crystal grain size is 0.5 to 1.37 zm, and more than 90% of the number of constituent crystal grains of the entire sintered body is within the range of 0.7 to 1.37 zm. A substrate material according to claim 1. 3) Tic with an average particle size of 1.5 gm or less. TiO2 30-40% (however, TiO2/(Ti
100 parts by weight of a basic component powder consisting of A-203 with a percentage of C + T i 02 ) of 5 to 15% by weight) and the remainder having an average particle size of 1.0 gm or less, and the following A, B, and C component powders (
However, the blending ratio of components A and B is within the range surrounded by KLMN in Figure 1). A method for manufacturing an alumina-based magnetic head substrate material characterized by sintering raw materials: A component = RO* AlI303 (R = Mg, M
n. One or more types of spinel represented by one or more of Ni, Co)
2.0-17.5 parts by weight. Component B = 0.2 to 2.0 parts by weight of Zr02. C component=Y2030.05 to 2 parts by weight.

Claims (1)

[Claims] 1) The percentage of TiO,/(TiC+TiO,) is 5 to
100 parts by weight of a component consisting of 30 to 40% by weight of a titanium compound of 15% by weight and the balance AfL203, and the following A, B, and C components of a specified percentage (however, the blending ratio of components A and B is enclosed by KLMN in Figure 1). (within range) and 0 for all compositions.
．． 2% by weight or less of oxide impurities, average crystal grain size of 1.3gm or less, area porosity of 0.5% or less, bending strength of 70kg/mm' or less, hardness of HRA93.
．． An alumina-based magnetic head substrate material made of a dense sintered body having a density of 0 or more 2'A component=RO・Ajl? 203 (R=Mg, Mn, N
one or more types of spinels represented by i, Co (one or more)
．． 0 to 17.5 parts by weight, component B = Zr02 0.2 to 2.0 parts by weight, component C - Y
20.05 to 2 parts by weight. 2) AlI3 03 , TiC, TiO2. Y, 03. A patent claim in which ZrO2 and spinel are uniformly dispersed, the average crystal grain size is 0.5 to 1.3 gm, and 90% or more of the number of crystal grains constituting the entire sintered body is within the range of 0.7 to 1.3 pm. The substrate material according to item 1. 3) TiC1Ti02 with an average particle size of 1.5 gm or less 3
0 to 40% by weight (however, TiO2/(TiC1Ti02)
(% by weight is 5-15%) and the remainder has an average particle size of 1.0μ
It consists of 100 parts by weight of component powder consisting of Au2O of less than m, and the following A, B, and C component powders (however, the blending ratio of A and B components is within the range surrounded by KLMN in Figure 1) at a predetermined percentage. mixture (however, the oxide impurity in the whole mixture is 0.2
A method for producing an alumina-based magnetic head substrate material, characterized by sintering a starting material consisting of a starting material consisting of: A component = RO・A sentence 203 (R = M, M. n Ni, Co, or more) ) 2.0 to 17.5 parts by weight of spinel type I or more represented by Component B-Z r 02 0, 2 to 2, 0 parts by weight, C
Ingredients = y2o30.05~2 times early part.